Liquid crystal displays have a structure including a liquid crystal cell held between two polarizing plates. In normally black mode liquid crystal displays, which display black image when the liquid crystal cell voltage is OFF, two polarizing plates (P1 and P2) are so placed that their transmission axes are orthogonal to each other as shown in FIG. 3. Polarizing plates are generally produced in the form of long films by a continuous process, and therefore, the film width is limited to at most few meters and generally limited to about 1 m. In recent years, however, a demand for larger screen liquid crystal displays has been increasing, and therefore, for example, polarizing plates applicable to displays with a diagonal size of more than 65 inches (about 1,640 mm) have been demanded. One of the most popular large screen televisions is of a wide type with a width-to-length ratio of 9:16. When two polarizing plates are placed with their transmission axes orthogonal to each other in such a liquid crystal display having a screen with different vertical and horizontal lengths, the width of one polarizing plate has to differ from that of the other polarizing plate in order to hold a liquid crystal cell between them, because they are each anisotropic. As shown in FIG. 1A, for example, when both the light source-side polarizing plate and the viewer-side polarizing plate to be used are cut from long polarizing plates (P11 and P12) each having a transmission axis in the direction of the width of the long film, one polarizing plate (P21) has to be cut in such a manner that the width of the long polarizing plate will correspond to the long side, and the other polarizing plate (P22) has to be cut in such a manner that the width of the long polarizing plate will correspond to the short side, so that two polarizing plates of the same size and with their transmission axes orthogonal to each other can be obtained. In this case, therefore, the length of the long side of the liquid crystal display is limited within the width of the polarizing plate, and, for example, a polarizing plate with a width of 1,400 mm or more is necessary for a 65 inch size television.
For such application to large screen liquid crystal displays, known methods include using a wide polyvinyl alcohol (PVA) film as a substrate (see for example Patent Literature 1), performing transverse stretching in the process of manufacturing a polarizing plate (see for example Patent Literature 2) and other methods of extending the width of the polarizing plate. However, wide films tend to have low uniformity or handleability, and the cost of facilities for the production of such a long wide film will be high. Therefore, such known methods are less practical.
On the other hand, as shown in FIG. 1B, for example, a long polarizing plate (P13) having a transmission axis in the longitudinal direction and another long polarizing plate (P14) having a transmission axis in the width direction may be used as a light source-side polarizing plate and a viewer-side polarizing plate, respectively. In this case, polarizing plates (P23 and P24) may be cut in such a manner that the widths of both long polarizing plates will correspond to the short side of a liquid crystal display, so that two polarizing plates of the same size and with their transmission axes orthogonal to each other can be obtained. Thus, the length of the short side of the liquid crystal display only has to be within the width of the polarizing plate, and this technique is applicable to the production of large screen liquid crystal displays without extending the width of the long polarizing plate, in contrast to the case shown in FIG. 1A. Examples of the polarizing plate having a transmission axis in the width direction include iodine polarizing plates that are produced by allowing iodine to adsorb to a hydrophilic polymer film such as a polyvinyl alcohol film and uniaxially stretching the film in the longitudinal direction. A commercialized polarizer having a transmission axis in the longitudinal direction is a reflective linear polarizer produced by transversely stretching a resin laminate of two or more layers produced with two or more birefringent resins, such as D-BEF commercially available from 3M.
However, the reflective linear polarizer such as D-BEF has the disadvantage that it reduces visibility, when it is incorporated in a liquid crystal display so as to reflect external light. Thus, a laminated polarizing plate is disclosed in which a reflective linear polarizer and an absorptive polarizer such as an iodine polarizer are so placed that their transmission axes coincide with each other (see for example Patent Literature 3). However, since the iodine-based absorptive polarizer (Pa) has a transmission axis in the width direction as mentioned above, as shown in FIG. 2A, the lamination of the long absorptive polarizer (Pa) itself and a reflective linear polarizer (Pr) having a transmission axis in the longitudinal direction, such as D-BEF, cannot make their transmission axes parallel to each other. In order to make their transmission axes parallel to each other, pieces of the polarizers have to be cut one by one in forming a laminate, and therefore, a long polarizing plate is not obtainable, which leads to low productivity. In addition, when an absorptive polarizer having a transmission axis in the width direction, such an iodine polarizing plate, is used, there is a problem in which the length of the long side of the liquid crystal display is limited within the width of the polarizing plate as in the case shown in FIG. 1A.
Patent Literature 1: Japanese Patent Application Laid-Open (JP-A) No. 2002-28939
Patent Literature 2: JP-A No. 11-183726
Patent Literature 3: Japanese Patent Application National Publication (Laid-Open) No. 09-507308